Why this is the case is, imo, obvious. Save the world stories are easy to tell and easy to understand. The sides are clear cut, there is no moral ambiguity and its easy to dehumanize the oppositions. Even if they are humans, why feel bad when killing someone so evil and deranged that he wants to destroy the world?
Actually, I don't think it's as clear-cut as all that. I think there's an aspect of sequel-itis in there as well: the first time you tell the story, you get to set the stakes; the next time everything needs to be bigger and better; and the next, and the next, and... The end-point of this, of course, is the stakes become "the end of everything". Problem is, there's not really anywhere to go after that.
So I want to know what type of stories do you run?
A whole bunch, but I don't think I've done a "save the world" for a
very long time. (Despite what some of my players would say - in at least one case they were convinced the TPK led to the destruction of the world, but that was never the stake; all that happened was a very big, very nasty dragon was let loose.)
Most of my recent campaigns have been local stuff. Even the campaigns that went to Epic level were about making a fundamental change to the underlying setting, but not about saving the world.
Let's think...
"Shackled City" isn't a save-the-world plot - save-the-city certainly, with a side-order of defeating a powerful BBEG, but not one intent (and able) on destroying or enslaving the world.
"The Company of the Black Hand" was a WFRP (2nd Ed) campaign that was based on the "Black Company" novels, and that dealt with the well-being of a region. In that case, the PCs' victory actually made things
worse - the BBEG
was evil, but she was also a very strong ruler for a city in a precarious position; by removing her, the PCs left a power vacuum that destabilised the region.
"The First Rebellion" was a Dark Times SWSE campaign that started with the PCs (and, in particular, the Jedi PC) fleeing a Star Destroyer as Order 66 was issued, and dealt mostly with survival. They did organise a fight-back, but it wasn't going to end well. (Though the campaign fizzled before we got into that - at the end, the PCs had just been betrayed by their main allies.)
"Cavcari's Last Incantation" was a FR 3.5e campaign that was based on an underlying (non-canonical) 'truth' that "everything that has a beginning must have an end" - including the deities. Thus, the PCs were going to have a choice - do they remove that limitation, or not? (That campaign died quickly; I may recycle much of it for my current group.)
"Tracks of Lightning" was a 3.5e Eberron campaign set in the Mournland, and dealing with efforts to reconnect the Lightning Rail. The BBEG was the Lord of Blades, though due to a contraction of the timeline he was merely headed off rather than destroyed. Still, a regional problem.
"The Eberron Code" (again, 3.5e) was a 3 year campaign that did reach high levels. This one was ultimately about the demon bound within the Silver Flame, and left the PCs a choice: do they extinguish the Flame, leave it as-is, or attempt to bind the demon more tightly and thus 'cleanse' the Flame. Regardless of their choice, the world would be
changed by their actions, but it wasn't being
saved.
"Imperial Fist" was another Dark Times SWSE campaign, in which the PCs were cast as Imperial agents charged with hunting down and eliminating Jedi terrorists. This was a regional, not universal, issue.
And I think that's all the campaigns I've run in the last decade (false starts excluded). Guess I'm due for a "save the world"!
